Vascular Remodeling by a Guidewire Insertion in the Normal Rabbit Iliac Artery

ABSTRACT

BACHGROUND AND OBJECTIVE: The behavior of vascular remodeling is not exactly known to occur in the normal vessel, athough adaptive and pathologic remodeling occurs in atherosclerosis. We examined the behavior of vascular remodeling with an abrupt reduction of luminal area by indwelling a guidewire within an iliac artery in a normal rabbit. MATERIALS AND METHODS: New Zealand white rabbits (n=17, body weight =3.2+/-0.2kg) were dissected to expose the left femoral artery and indwelling a guidewire(diameter=0.035") was inserted toward the aorta in order to induce the acute irreversible luminal thrombus within the left iliac artery. Four weeks later, the manipulated iliac arteries were harvested. RESULTS: All iliac arteries were patent. There were three patterns of vascular remodeling in microscopic examination. In the first group(n=8), a simple concentric luminal dilatation with centrally organized thrombus was shown. The arterial wall showed increased wall thickness and a number of medial smooth muscle cell(SMC). The second group(n=8) showed luminal thrombus with neointimal hyperplasia, which consisted of migration and proliferation of medial SMC, and regression of the original medial layer. Vascular lumen was markedly enlarged. It appeared as wide lumen with extrusion of the guidewire toward outside of the new lumen and a transition from an old medial smooth muscle layer which had the original SMC in structure to a new layer consisting of linear SMC proliferation in intimal hyperplasia. Finally, sinusoidal plexus formation was seen within a thrombus in only one case. This sinusoidal vascular structure contained SMC with an extracellular matrix. CONCLUSION: We observe the pluripotent capability of vascular remodeling following acute luminal loss by a guidewire insertion in the normal rabbit iliac artery.